How do you solve #x^2-8x=9#?

1 Answer
Jun 16, 2018

Answer:

See a solution process below:

Explanation:

First, put the equation in standard form:

#x^2 - 8x = 9#

#x^2 - 8x - color(red)(9) = 9 - color(red)(9)#

#x^2 - 8x - 9 = 0#

Next, factor the left side of the equation as:

#(x + 1)(x - 9) = 0#

Now, solve each term on the left side of the equation for #0#:

Solution 1:

#x + 1 = 0#

#x + 1 - color(red)(1) = 0 - color(red)(1)#

#x + 0 = -1#

#x = -1#

Solution 2:

#x - 9 = 0#

#x - 9 + color(red)(9) = 0 + color(red)(9)#

#x - 0 = 9#

#x = 9#

The Solution Set Is:

#x = {-1, 9}#